[larssorenson]

Yes, the author is specifically refering to KVM (https://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine) which was merged into the Linux kernel in 2007.

Whereas Docker (https://en.wikipedia.org/wiki/Docker_(software)) was first released in 2013.

[indigodaddy]

Believe that the author was actually specifically referring to LXC (misnamed as "LXE" in the article), with his Docker reference.